Charles Ellicott Commentary 2 Samuel 23:16

"And the three mighty men brake through the host of the Philistines, and drew water out of the well of Beth-lehem, that was by the gate, and took it, and brought it to David: but he would not drink thereof, but poured it out unto Jehovah." — 2 Samuel 23:16 (ASV)

Poured it out unto the Lord. — The brave act of the three heroes shows strikingly the personal power of David over his followers and the enthusiasm with which he inspired them. Yet, on the other hand, David would not permit his own longing to be gratified by the risk to men’s lives. Taking the water, therefore, he poured it out unto the Lord. The word is the technical term for the sacrificial libation, and David assimilated his act to a sacrifice by a solemn consecration of this dangerously won water to the Lord.